This invention relates to a novel liquid crystalline compound which can demonstrate favorable properties principally in a twisted nematic liquid crystal composition and a liquid crystal composition having favorable properties using said novel liquid crystalline compound.
A liquid crystal display element utilizes an optical anisotropy and a dielectric anisotropy which a liquid crystalline material possesses. As a display mode therefor, there are known a twisted nematic mode (TN), a super twisted nematic mode (STN), a dynamic scattering mode (DS), a guest-host mode (G-H), DAP mode and others. As a driving mode therefor, there are known a static-driving mode, a time-sharing driving mode, an active-matrix driving mode, a dual frequency driving mode and others. The properties of liquid crystalline materials used for these various liquid crystal display elements vary depending on the application of the elements, but liquid crystalline materials are required to be stable to external environmental factors such as moisture, air, heat, light, etc. and to show a liquid crystal phase over a wide temperature range around room temperature, with a lower viscosity and a lower driving voltage. In addition, a liquid crystalline material generally used for a liquid crystal display element is composed of several to twenty liquid crystalline compounds for providing the optimum dielectric anisotropy (xcex94∈) or optical anisotropy (xcex94n) which is required for individual display elements. In view of this, there has been required a compatibility with other liquid crystalline compounds, particularly in recent years, a good low-temperature compatibility from the demand for application under various environments.
A liquid crystalline compound having as a substituent a fluorine atom at the end generally shows a lower dielectric anisotropy (xcex94∈) and optical anisotropy (xcex94n) as compared with a compound having a cyano group as a substituent, but has a remarkably superior chemical stability to that of the cyano-substituted compound and is considered to cause a less production of ionic impurities due to a change with time. Therefore, the fluorine-containing compounds have been actively used for various modes including an active-matrix mode. The recent trend of development in this field is directed to making a small-sized liquid crystal element including a portable TV and lowering in driving voltage in compliance with the demand for a lower voltage. In order to achieve this object, the development of a compound having a high dielectric anisotropy (xcex94∈) is active.
In order to increase a dielectric anisotropy (xcex94∈) in the fluorine-containing compound, it is effective to increase the substitution number of a fluorine atom, which is a procedure usually carried out by those skilled in the art. However, it has been empirically realized by those skilled in the art that there is a proportional relationship between the substitution number of a fluorine atom and the viscosity of the compound, and further that there is an inverse relationship between the. substitution number of a fluorine atom and the temperature range of a liquid crystal phase. Accordingly, it has been considered to be difficult to improve a dielectric anisotropy (xcex94∈) only, while inhibiting an increase in the viscosity and a reduction in the temperature range of a liquid crystal phase. As an example of the compounds multi-substituted with fluorine atoms, those having the following structure are disclosed. 
The dielectric anisotropy values (xcex94∈) of the compounds (a), (b) and (c) are high in the order of (c) greater than (b) greater than (a). However, the compound (c) is not appreciably good in respect of a compatibility with other liquid crystalline compounds, especially, a low temperature compatibility. On the other hand, the compound (d) shows an example wherein a fluorine atom is laterally substituted on the phenyl ring to which R is attached, but this compound is not so appreciably good in respect of compatibility.
It is an object of this invention to provide a novel liquid crystalline compound having a relatively low viscosity, a high dielectric anisotropy, a low optical anisotropy and an excellent compatibility with other known liquid crystalline compounds, in particular, an excellent low temperature compatibility, and a liquid crystal composition containing the same.
We have investigated various compounds in an effort to solve the aforesaid problems and found as a liquid crystalline compound with a high dielectric anisotropy, a compound having a phenylbenzoate moiety and a fluorine atom substituted at the ortho-position to the ester carbonyl group. As a result of further study of its physical properties, it has been found that the fluorine atom substituted at the ortho-position to the ester carbonyl group of the phenylbenzoate moiety can serve to improve the viscosity and suppress a reduction in a temperature range of a liquid crystal phase and to exhibit an extremely higher dielectric anisotropy than that as we initially expected and further to accomplish a remarkable effect on improvement in a compatibility with other liquid crystalline compounds, in particular, in a low temperature compatibility, which leads to the completion of the present invention directed to a novel liquid crystalline material.
In the first aspect, the invention relates to phenylbenzoate derivatives represented by formula (1) 
wherein R1 is a hydrogen atom or a straight or branched-chain alkyl group of 1-10 carbons, one or two non-adjacent CH2 groups of which can be replaced by an oxygen atom or a group of xe2x80x94CHxe2x95x90CHxe2x80x94; X is a hydrogen atom or a halogen atom; A and B each independently represent a 1,4-phenylene group or a trans-1,4-cyclohexylene group, which may be substituted by one or more halogen atoms; Z1 and Z2 each independently represent xe2x80x94CH2CH2xe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94, xe2x80x94Cxe2x89xa1Cxe2x80x94, xe2x80x94(CH2)4xe2x80x94 or a covalent bond; m and n each independently represent 0 or 1.
Where R1 in formula (1) is a group other than a hydrogen atom, the following groups are included as specific groups.
Where R1 is a straight-chain group, it includes an alkyl group of 1-10 carbons, an alkoxy group of 1-9 carbons, an alkoxyalkyl group of 2-9 carbons, an alkoxyalkoxy group of 2-8 carbons, an alkenyl group of 2-11 carbons, an alkenyloxy group of 2-10 carbons, an alkenyloxyalkyl group of 3-10 carbons and an alkoxyalkenyl group of 3-10 carbons.
Where R1 is a branched-chain group, it includes an alkyl group of 3-10 carbons, an alkoxy group of 3-9 carbons, an alkoxyalkyl group of 4-9 carbons, an alkoxyalkoxy group of 4-8 carbons, an alkenyl group of 3-11 carbons, an alkenyloxy group of 3-10 carbons, an alkenyloxyalkyl group of 4-10 carbons and an alkoxyalkenyl group of 4-10 carbons.
Where R1 is a branched-chain group, in particular, an optically active group, the corresponding compound can be used as an additive to induce a twisted structure in a nematic liquid phase or as a component for a chiral smectic liquid crystal having a ferroelectricity.
One preferred embodiment in the first aspect of this invention is a phenylbenzoate derivative of formula (1) wherein m=n=0, both Z1 and Z2 are a covalent bond.
Another preferred embodiment in the first aspect of this invention is a phenylbenzoate derivative of formula (1) wherein m=1, n=0, either of Z1 and Z2 is a covalent bond, A is a trans-1,4-cyclohexylene group.
A still another preferred embodiment in the first aspect of this invention is a phenylbenzoate derivative of formula (1) wherein m=1, n=0, either of Z1 and Z2 is a covalent bond, A is a 1,4-phenylene group.
A still another preferred embodiment in the first aspect of this invention is a phenylbenzoate derivative of formula (1) wherein m=1, n=1, and A and B each are a trans-1,4-cyclohexylene group.
A still another preferred embodiment in the first aspect of this invention is a phenylbenzoate derivative of formula (1) wherein m=1, n=1, and A is a trans-1,4-cyclohexylene group and B is a 1,4-phenylene group.
A still another preferred embodiment in the first aspect of this invention is a phenylbenzoate derivative of formula (1) wherein m=1, n=1, and A is a 1,4-phenylene group and B is a trans-1,4-cyclohexylene group.
A still another preferred embodiment in the first aspect of this invention is a phenylbenzoate derivative of formula (1) wherein m=1, n=1, and A and B each are a 1,4-phenylene group.
In the second aspect, the invention relates to liquid crystal compositions composed of at least two components, which comprise at least one phenylbenzoate derivative represented by formula (1) as defined in the first aspect of this invention.
One preferred embodiment in the second aspect of this invention is a liquid crystal composition which comprises as a first component at least one of the phenylbenzoate derivatives represented by formula (1) as defined in the first aspect of this invention and as a second component one or more compounds selected from the group consisting of the compounds of formulae (2), (3) and (4) 
wherein R2 is an alkyl group of 1-10 carbons, Y is F or Cl, Q1, and Q2 each independently represent H or F, r is 1 or 2, and Z3 and Z4 each independently represent xe2x80x94CH2CH2xe2x80x94 or a covalent bond.
An another preferred embodiment in the second aspect of this invention is a liquid crystal composition which comprises as a first component at least one phenylbenzoate derivative of formula (1) as defined in the first aspect of this invention and as a second component one or more compounds selected from the group consisting of the compounds of formulae (5), (6), (7), (8) and (9) 
wherein R3 is an alkyl group of 1-10 carbons or an alkenyl group of 2-10 carbons. In any case, an optional methylene group (xe2x80x94CH2xe2x80x94) may be replaced by an oxygen atom (xe2x80x94Oxe2x80x94), but two or more methylene groups are not consecutively replaced by an oxygen atom, Z5 is xe2x80x94CH2CH2xe2x80x94, xe2x80x94COOxe2x80x94 or a covalent bond, Q3 and Q4 represent H or F, C stands for a cyclohexane ring, a benzene ring or a 1,3-dioxane ring, and s is 0 or 1, 
wherein R4 is an alkyl group of 1-10 carbons, Q5 represents H or F, and k is 0 or 1, 
wherein R5 is an alkyl group of 1-10 carbons, D stands for a cyclohexane ring or a benzene ring, Q6 and Q7 each independently represent H or F, Z6 is xe2x80x94COOxe2x80x94 or a covalent bond, and h is 0 or 1,
R6xe2x80x94(E)xe2x80x94Z7xe2x80x94(F)xe2x80x94R7xe2x80x83xe2x80x83(8)
wherein R6 and R7 each independently represent an alkyl, an alkyloxy or alkyloxymethyl group of 1-10 carbons, E stands for a cyclohexane ring, a pyrimidine ring or a benzene ring, F stands for a cyclohexane ring or a benzene ring, and Z7 is (xe2x80x94Cxe2x89xa1Cxe2x80x94), xe2x80x94COOxe2x80x94, xe2x80x94CH2CH2xe2x80x94or a covalent bond, 
wherein R8 is an alkyl or alkyloxy group of 1-10 carbons, R9 is an alkyl, alkyloxy or alkyloxymethyl group of 1-10 carbons, G stands for a cyclohexane ring or a pyrimidine ring, H and J each independently represent a cyclohexane ring or a benzene ring, Z8 is xe2x80x94COOxe2x80x94, xe2x80x94CH2CH2xe2x80x94or a covalent bond, Z9 is xe2x80x94Cxe2x89xa1Cxe2x80x94, xe2x80x94COOxe2x80x94 or a covalent bond, and Q8 is H or F.
In the third aspect, the invention relates to a liquid crystal display element using a liquid crystal composition comprising at least two components, which comprises at least one phenylbenzoate derivative represented by formula (1) as defined in the first aspect of this invention.
A preferred embodiment of the liquid crystal composition used in the third aspect of this invention is a liquid crystal composition described in any embodiments of the second aspect of this invention.
Examples of the preferred embodiments of the phenylbenzoate derivatives represented by formula (1) in the first aspect of this invention include the compounds represented by the following formulae (1-a)-(1-g). 
wherein R is a hydrogen atom or a straight or branched-chain alkyl group of 1-9 carbons, one or two non-adjacent CH2 groups of which may be replaced by an oxygen atom or xe2x80x94CHxe2x95x90CHxe2x80x94group, X is a hydrogen atom or a halogen atom, Z1 and Z2 each independently are xe2x80x94CH2CH2xe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94, xe2x80x94Cxe2x89xa1Cxe2x80x94 or a covalent bond.
Preferred compounds of formula (1-b) are more specifically referred to by the following compounds. 
wherein R is a hydrogen atom or a straight or branched-chain alkyl group of 1-9 carbons, one or two non-adjacent CH2 groups of which may be replaced by an oxygen atom or xe2x80x94CHxe2x95x90CHxe2x80x94 group, X is a hydrogen atom or a halogen atom.
Preferred compounds of formula (1-c) are more specifically referred to by the following compounds. 
wherein R is a hydrogen atom or a straight or branched-chain alkyl group of 1-9 carbons, one or two non-adjacent CH2 groups of which may be replaced by an oxygen atom or xe2x80x94CHxe2x95x90CHxe2x80x94 group, X is a hydrogen atom or a halogen atom.
Preferred compounds of formula (1-d) are more specifically referred to by the following compounds. 
wherein R is a hydrogen atom or a straight or branched-chain alkyl group of 1-9 carbons, one or two non-adjacent CH2 groups of which may be replaced by an oxygen atom or xe2x80x94CHxe2x95x90CHxe2x80x94 group, X is a hydrogen atom or a halogen atom.
Preferred compounds of formula (1-e) are more specifically referred to by the following compounds. 
wherein R is a hydrogen atom or a straight or branched-chain alkyl group of 1-9 carbons, one or two non-adjacent CH2 groups of which may be replaced by an oxygen atom or xe2x80x94CHxe2x95x90CHxe2x80x94 group, X is a hydrogen atom or a halogen atom.
Preferred compounds of formula (1-f) are more specifically referred to by the following compounds. 
wherein R is a hydrogen atom or a straight or branched-chain alkyl group of 1-9 carbons, one or two non-adjacent CH2 groups of which may be replaced by an oxygen atom or xe2x80x94CHxe2x95x90CHxe2x80x94 group, X is a hydrogen atom or a halogen atom.
Preferred compounds of formula (1-g) are more specifically referred to by the following compounds. 
wherein R is a hydrogen atom or a straight or branched-chain alkyl group of 1-9 carbons, one or two non-adjacent CH2 groups of which may be replaced by an oxygen atom or xe2x80x94CHxe2x95x90CHxe2x80x94 group, X is a hydrogen atom or a halogen atom.
A liquid crystal composition according to the second aspect of this invention may preferably contain one or more of the phenylbenzoate derivatives of formula (1) in an amount of 0.1-99% by weight for producing very good characteristics.
More specifically, the liquid crystal composition provided by the present invention can be completed by blending a first component containing at least one phenylbenzoate derivative of formula (1) with a compound optionally selected from the compounds of formulae (2)-(9) in compliance with the object of a liquid crystal composition.
As the compounds of formulae (2)-(4) used in the invention, the following compounds are preferred, in which R1 is an alkyl or alkoxy group. 
The compounds of formulae (2)-(4) have a positive dielectric anisotropy and very good thermal and chemical stabilities, and they are essential in preparing a liquid crystal composition for TFT (AM-LCD) which requires a high reliability, in particular, a high voltage holding rate or a high specific resistance.
The amount of the compounds of formulae (2)-(4) used may be in the range of 1-99% by weight, preferably 10-97% by weight, based on the total weight of a liquid crystal composition, in the preparation of a liquid crystal composition for TFT. More preferably, it is 40-95% by weight. In this case, the composition may partly contain the compounds of formulae (5)-(9). In the preparation of a liquid crystal composition for STN display mode or usual TN display mode, the compounds of formulae (2)-(4) can be used.
As the compounds of formulae (5)-(7) of the invention, the following compounds are preferable, in which R2, R3 and R4 are an alkyl or alkenyl group and Rxe2x80x2 is an alkylene group. 
The compounds of formulae (5)-(7) have a positive and high dielectric anisotropy and are used especially for reducing a threshold voltage. They are also used for adjusting a viscosity, adjusting an and broadening a nematic phase range such as an increase in clearing point or the like. Further, they are used for improving steepness.
As the compounds of formulae (8) and (9), the following compounds are preferable, in which R5, R6, R7 and R8 are an alkyl or alkenyl group. 
The compounds of formulae (8) and (9) are those which have a negative or weakly positive dielectric anisotropy. The compounds of formula (8) are used mainly for reducing viscosity and/or for adjusting an. The compounds of formula (9) are used for broadening a nematic phase range such as an increase in a clear point and/or for adjusting xcex94n.
The compounds of formulae (5)-(9) are essential particularly for the preparation of a liquid crystal composition for STN display mode and usual TN display mode.
The amount of the compounds of formulae (5)-(9) used may be in the range of 1-99% by weight in the preparation of a liquid crystal composition for usual TN display mode and STN display mode, and 10-97% by weight is preferable. 40-95% by weight is more preferable. In this case, the compounds of formulae (2)-(4) may also be used in part.
The use of the present liquid crystal composition for a TFT liquid crystal display element can improve the steepness and the viewing angle. Since the compounds of formula (1) are of a low viscosity, the response rate of the liquid crystal display element using those compounds is improved.
The liquid crystal compositions used according to the invention are prepared by the processes conventional per se. In general, there are employed the processes wherein various components are mutually dissolved at an elevated temperature. The liquid crystal materials of the invention are improved and optimized in compliance with the use as intended by using suitable additives. Such additives are well known to those skilled in the art and also described in detail in literatures. Usually, a chiral dopant is added for inducing helical structures of the liquid crystal to control necessary twist angle and preventing a reverse twist.
Further, the liquid crystal compositions of the present invention can be used as liquid crystal materials for guest-host (GH) mode by incorporating therein dichronic dyes such as merocyanines, styryls, azo, azomethines, azoxy, quinophthalones, anthraquinones, tetrazines or the like. Alternatively, they can be used as liquid crystal materials for NPCA formed by micro-capsulation of nematic liquid crystals, or as liquid crystal materials for polymer dispersed liquid crystal display elements (PDLCD), a typical example of which is a polymer network liquid crystal display element (PNLCD) wherein a three-dimensional network polymer is formed in the liquid crystal. In addition, they can be used as liquid crystal materials for electrically controlled birefringence (ECB) mode and dynamic scattering (DS) mode.
The nematic liquid crystal compositions containing the phenylbenzoate derivatives of the invention can be illustrated by the following Composition Examples.



















(Process for the Preparation of the Present Phenylbenzoate Derivatives)
For example, the preferred compounds represented by formula (1-a) can be prepared by reacting a lithium reagent generally known such as an alkyl lithium with 3-fluoroalkylbenzenes (1) to introduce lithium at the 4-position thereof, followed by reacting with a formylating agent such as formylpiperidine or N,N-dimethylformamide to form the corresponding aldehyde derivative and subsequently reacting with a suitable oxidizing agent to afford the corresponding carboxylic acid derivative (2).
Alternatively, the carboxylic acid derivative (2)g may be prepared by reacting the lithium derivative with CO2. Alternatively, an acid chloride derivative of the compound (2) may be prepared by reacting the compounds (1) with oxalyl chloride according to Friedel-Crafts reaction. Subsequently, the carboxylic acid derivative (2) can be reacted with 3,4,5-trifluorophenol, in accordance with a general esterification process, for example, using as an acid catalyst, a mineral acid such as hydrochloric acid, sulfuric acid, an organic acid such as p-toluenesulfonic acid, a nonaqueous ion exchange resin such as Amberlite, or as a catalyst N,N-dicyclohexylcarbodiimide (DCC) to prepare the compounds (1-a). Alternatively, the compounds (1-a) may be prepared by reacting the compound (2) with thionyl chloride to form the corresponding acid chloride, followed by the reaction with 3,4,5-trifluorophenol in the presence of a base such as pyridine. 
One of the starting materials, 3,4,5-trifluoro-phenol can be prepared using 3,4,5-trifluorobromobenzene as a starting material. More specifically, a Grignard reagent prepared from 3,4,5-trifluorobromobenzene is reacted with t-butyl hydroperoxide according to the method by S. O. Lawesson et al. (J. Am. Chem. Soc., 81, 4230(1959)), or the Grignard reagent is treated with a trialkyl borate to form the corresponding borate derivative and then oxidized with hydrogen peroxide aqueous solution according to the method by R. L. Kidwell et al. (Org. Synth., V, 918(1973)). 
The compounds represented by formula (1-b) can be prepared according to the following reaction route. For the preparation of the compounds (1-b-1), alkyl substituted cyclohexanones (3) are reacted with a Grignard reagent prepared from a 3-fluorobromobenzene derivative (4) to form the corresponding alcohol derivatives (5), which are dehydrated using as an acid catalyst, a mineral acid such as 5 hydrochloric acid, sulfuric acid, an organic acid such as p-tolenesulfonic acid, a nonaqueous ion exchange resin such as Amberlite; followed by a catalytic hydrogenation in the presence of a noble metal catalyst such as Pt, Rh, and Pd to afford 1-(4-alkylcyclohexyl)-3-fluorobenzene derivatives (6). The compounds (1-b-1) can be prepared in the same manner as described above for the preparation of the compounds (1-a), by forming the corresponding carboxylic acid derivatives via the formation of the lithium derivative, followed by esterification with 15 3,4,5-trifluorophenol. 
For the preparation of the compounds (1-b-2), 3-fluorophenol derivatives (7) as a starting material are reacted with sodium hydride, followed by protecting the phenolic hydroxyl group with chloromethyl methyl ether or the like to give the intermediates (8). The compounds (8) are treated in the same manner as described above for the preparation of the compounds (1-a) to give the ester intermediates (9). The compounds (9) are deprotected in the presence of a mineral acid such as hydrochloric acid, sulfuric acid, etc., and then reacted with an acid chloride prepared from the reaction of alkylcyclohexycarboxylic acids (11) and thionyl chloride in the presence of pyridine. 
For the preparation of the compounds (1-b-3), the corresponding ylide compound prepared by reacting ethyl diethylphosphinoacetate with a base such as an alkyl lithium, sodium alcoholate, potassium t-butoxide, etc. is reacted with alkyl substituted cyclohexanones (3) to form intermediates (12) having two carbon atoms increased, the olefin moiety is reduced by catalytic hydrogenation in the presence of a noble metal catalyst such as Pt, Rh, Pd, etc. and further the ester moiety is reduced with lithium aluminum hydride to give the corresponding alcohol derivatives (13). The derivatives (13) are reacted with pyridinium chlorochromate (PCC) or subjected to DMSO oxidation (Swern oxidation) to give the corresponding aldehyde derivatives (14). The derivatives (14) are reacted with a Grignard reagent prepared from the compounds (4) to form the alcohol products (15) which are then dehydrated using as an acid catalyst a mineral acid such as hydrochloric acid, sulfuric acid, etc., an organic acid such as p-toluenesulfonic acid, etc. or a nonaqueous ion exchange resin such as Amberlite, etc. and further subjected to catalytic hydrogenation in the presence of a noble catalyst such as Pt, Rh, Pd, etc. to prepare 1-(4-alkylcyclohexyl)-2-(3-fluorophenyl)ethanes (16). The compounds (16) can be treated in the same manner as described above for the preparation of the compounds (1-a) to prepare the compounds (1-b-3). 
The compounds of formula (1-c) can be prepared according to the following reaction route. For the preparation of the compounds (1-c-1), a starting material, 4-alkyliodobenzenes (17) are reacted with a Grignard reagent prepared from the compounds (4) in the presence of a catalyst such as palladium chloride, etc. to form the corresponding biphenyl derivatives (18). The derivatives (18) can be treated in the same manner as described above for the preparation of the compounds (1-a) to prepare the compounds (1-c-l). Further, the compounds (1-c-2) can be prepared by esterification of the above compounds (10) with 4-alkyl substituted benzoic acid derivatives (19). For the preparation of the compounds (1-c-3) and (1-c-4), a starting material, 3-fluorobenzaldehydes (20) are protected for the aldehyde moiety with ethylene glycol in the presence of an acid catalyst and then treated in the same manner as described for the preparation of the compounds (1-a) to form the corresponding ester products (22). The ester products (22) are deprotected in the presence of an acid catalyst such as formic acid, acetic acid, etc. to form the compounds (23) which are then coupled with a Wittig reagent prepared from a 4-alkylbenzyl iodide to prepare the compounds (1-c-4). Subsequently, the compounds (1-c-4) can be subjected to catalytic hydrogenation in the presence of a noble catalyst such as Pt, Rh, Pd, etc. to prepare the compounds (1-c-3). 
For the preparation of the compounds (1-c-5), 3-fluoroiodobenzene derivatives (24) are reacted with oxalyl chloride according to Friedel-Crafts reaction to form the corresponding acid chloride (25) which is then reacted with trifluorophenol in the presence of a base such as pyridine, etc. to form the corresponding ester products (26). The ester products (26) can be coupled with 2-(4-alkylphenyl)acetylenes (27) according to any known method to prepare the compounds (1-c-5). 
The compounds represented by formula (1-e) can be prepared by the aforesaid reaction procedures. For example, the compounds (1-e-1) and (1-e-2) can be prepared via the same reaction route as described above for the preparation of the compounds (1-c-1), by using 4-(4-alkylcyclohexyl)iodobenzenes (27) or 1-(4-alkylcyclohexyl)-2-(4-iodophenyl)ethanes (28) instead of the starting materials (17). Other compounds of formula (1-e) can be prepared. Further, the compounds of formula (1-f) can be prepared by choice of suitable starting materials and the above reaction procedures or in combination with other known reaction procedures.